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浏览次数:发布时间:2017年05月11日

The Space Shuttle

Space shuttles go back and forth between Earth and space. The first one flew on April 12, 1981. A space has four main parts. They are the orbiter, the fuel tank, and two rocket boosters.

  The orbiter looks like an airplane. It carries the crew. A huge tank is attached to the orbiter. It holds fuel for the orbiters engines. A rocket booster is on each side of the tank. These fire on liftoff. In two minutes, the rockets run out of fuel and fall off. Parachutes slow their drop to the sea. Then boats tow them to shore. Rockets can be used as many as 20 times. The big tank runs out of fuel in eight minutes. It falls and breaks apart over the sea. Now the orbiter enters its orbit.

  There may be up to seven crew members on board the orbiter. They do tests. They might lanch satellites. In 1999, a shuttle went up to fix the Hubble telesope. The Hubble is as big as bus. The shuttle caught it. The telecope was held in cargo bay. Thats an open place like the back of a pickup truck. The crew worked out in space to make repairs. They wore space suits. They were attacthed to the shuttle by a long line. A robot arm put the Hubble back in orbit,

  When its time to come home, the orbiters engines fire. This slows the shuttle, and it drops from orbit. Tiles protect the shuttle from heat caused by entering Earths atmosphere. The shuttle then acts like an airplane. It glides to a landing on a runway.

 

 





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